Escherichia coli and other Enterobacteriaceae Infections
Enterobacteriaceae—a family of mostly aerobic, gram-negative bacilli—cause local and systemic infections, including an invasive diarrhea that resembles shigellosis and, more often, a noninvasive, toxin-mediated diarrhea that resembles cholera. With other bacilli of this family, Escherichia coli causes most nosocomial infections.
The prognosis in mild to moderate infection is good. But severe infection requires immediate fluid and electrolyte replacement to avoid fatal dehydration, especially among children, in whom the risk of death may be quite high.
The incidence of E. coli infection is highest among travelers returning from other countries, particularly Mexico (noninvasive), Southeast Asia (noninvasive), and South America (invasive). E. coli infection also causes other diseases, especially in people whose resistance is low.
Causes
Although some strains of E. coli exist as part of the normal GI flora, infection usually comes from nonindigenous strains. For example, noninvasive diarrhea results from two toxins produced by enterotoxigenic or enteropathogenic strains of
E. coli. These toxins interact with intestinal juices and promote excessive loss of chloride and water. In the invasive form, E. coli directly invades the intestinal mucosa without producing enterotoxins, thereby causing local irritation, inflammation, and diarrhea. Normal strains can cause infection in immunocompromised patients.
E. coli. These toxins interact with intestinal juices and promote excessive loss of chloride and water. In the invasive form, E. coli directly invades the intestinal mucosa without producing enterotoxins, thereby causing local irritation, inflammation, and diarrhea. Normal strains can cause infection in immunocompromised patients.
Transmission can occur directly from an infected person or indirectly by ingestion of contaminated food or water or contact with contaminated utensils. Incubation takes 12 to 72 hours.
Complications
Bacteremia, severe dehydration, life-threatening electrolyte disturbances, acidosis, and shock can result.
Assessment
Recent foreign travel, ingestion of contaminated food or water, or recent close contact with a person experiencing diarrhea may be part of the patient’s history.
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